JP2014506545A - Aircraft with reduced environmental impact - Google Patents

Abstract

  The present invention relates to an aircraft with reduced environmental impact and having two turboprop engines 10 mounted at the rear of the aircraft. The acoustic masking device has an acoustic masking element 33, such as a flap 33, which is movable between a position retracted into the wing and a position extended rearward of the wing. In its extended position, the flap 33 blocks the noise region 18 generated forward by the turboprop engine to reduce noise perception on the ground.

Description

  The present invention relates to an aircraft with reduced environmental impact.

  In the field of short- to medium-range aircraft and in the general aviation industry, the optimization of fuel use is an important item for profit.

  Traditionally, these aircraft were equipped with turbojets, a compromise between energy costs and environmental impact. In fact, other propulsion systems, such as propulsion engines with counter-rotating propellers, can save 20% of fuel, but are often ignored due to the undesirable noise that occurs. The noise sources to consider for this type of engine are due to the blade drive frequency and its harmonics, which are low frequency noises that are difficult to mask (propellers themselves). Noise and interaction noise between propellers.

  Applicants have discovered that the dominant noise is the noise resulting from the interaction between the propellers, since the noise of each propeller itself can be reduced. It can also be measured empirically and numerically, and the noise source region for a turboprop engine with a counter-rotating propeller is directed forward from the turboprop engine and concentrated on its axis. A first conical lobe, the apex of which is located approximately in the middle between the planes of the propellers, and a second conical which is directed rearward from the turboprop engine and concentrated on its axis A lobe that can be modeled by a second conical lobe whose apex is approximately midway between the planes of the propeller.

  Thus, in FR-A-2905366, the applicant discloses the advantage of blocking the upstream noise lobe by the wings and shows various solutions, in particular simply moving the wings backwards. In order to compensate for the loss of flight quality caused by moving the wing backward, the aerodynamic center is rearward compared to a conventional sweep wing, which adds an additional wing surface called the tail wing. The solution is to use forward wings to reduce the degree of movement.

  The present invention proposes a novel aircraft configuration that allows the noise generated by the engine to be reduced by at least one acoustic masking device.

  More particularly, the present invention comprises an aircraft with reduced environmental impact, comprising at least one propeller engine or jet engine attached to the rear of the aircraft to generate noise forward, and wings. In an aircraft in which noise generated by at least one engine is diffused into the noise region, the aircraft is at least one acoustic masking device in one retracted position and the other deployed position in at least one engine An acoustic masking device having at least one masking element movable between a deployed position where at least one masking element blocks a noise region to reduce perception of noise diffusion by To extend the chord in the root of the wing in the deployed position About Aircraft characterized in that it is moved backward.

  Preferably, turboprop type (ductless propeller) engines are used, for example to allow a significant reduction in fuel consumption.

  Applicants have found that the blade surface and its position relative to the engine, and the chord at the root, are the most important for the determination of acoustic masking parameters. Therefore, the efficiency of acoustic masking is improved by making the chord more backward and wider. In fact, the theoretical optimum position of the wings moved backward is located just in front of the engine, but this is not feasible due to the position (height) of the engine relative to the wings. The upper part of the tail unit functions as a mask for noise emitted downstream of each engine at a position above the engine room (RFN) position of the engine or the aircraft where the engine is located at the rear of the aircraft. For this reason, it is more suitable for masking by the wing part.

  When the at least one acoustic masking device is moved, the dimension (chord) is limited, and the wing part can be moved backward.

  The use of the at least one deployable acoustic masking element in fact allows noise reduction without the need to change wing position and does not require placement directly under the engine. Nevertheless, in order to increase the effect of acoustic attenuation, it is likewise possible to move the position of the wings backward as described above.

  According to a possible feature, the masking element is in the retracted position during the cruise phase and in the deployed position during the take-off phase, landing phase and / or approach phase.

  Thus, preferably noise reduction is performed during the flight phase when noise is least desirable, i.e. the aircraft is closer to the ground.

  The invention further relates to an aircraft further comprising a fuselage having a wing with two symmetrical wings, wherein at least one engine is mounted at the rear of the aircraft between the wing and the rear edge of the aircraft.

  The fact that the engine is not positioned directly above the wing is actually the result of losing the integrity of the engine or its rotor mast (failure of the engine's rotating elements, separators, etc.) It is possible to protect, thereby eliminating the need to apply reinforcement components there which increase the weight of the aircraft.

  The present invention further comprises an aircraft having a fuselage having a wing with two symmetrical wings and at least one horizontal tail unit, wherein the at least one engine has a wing and a horizontal tail at the rear of the aircraft. An acoustic masking device is mounted between the unit and associated with each of the wings, and at least one masking element of each acoustic masking device is retracted and deployed to extend the chord in each root of the wing It relates to aircraft that are movable between positions.

  Preferably, the at least one device comprises means for moving the at least one masking element from one position to another.

  According to an embodiment for optimizing the position and possible space of the masking device, the at least one masking element of the at least one device consists of at least one flap.

  In this case, the present invention can be realized in a conventional aircraft configuration by exchanging the internal flap with a flap of an acoustic masking device (eg at least one acoustic flap per wing), which is a low speed aerodynamic Reliable function (high lift) and acoustic masking element function.

  According to a feature, the at least one masking element comprises a main flap and at least one second flap.

  According to a particular embodiment, the main flap is rigid and the at least one second flap consists of flexible fibers.

  Such a mechanism allows a very strong backward movement in the deployed position, thereby enabling very efficient acoustic masking.

  The advantage of flexible fibers is that they can be wound and stored and allow the optimization of the required space, such as the space located behind the rear stringer of the wing.

  To achieve this objective, the at least one masking device comprises a winding / unfolding system that allows the flexible fibers to be wound and unfolded as required. The fiber is stretched in the deployed position.

  According to a feature, the at least one acoustic masking device comprises a system of one or more running parts and one or more running paths that serve to guide the movement of the running part during the movement of the at least one masking element. It has.

  An aircraft according to the present invention includes at least one fairing coupled to a wing, and the one or more traveling units and the one or more traveling path systems are respectively housed in the fuselage and the at least one fairing. Two runways are provided. This arrangement offers the possibility of a synergistic effect with the position of the auxiliary landing gear preferably housed in the fairing. In practice, noise reduction provides an opportunity to reduce fuel consumption. This is a specific case for a large wing range wing configuration (thus the ground stability of the aircraft requires a long runway) but the following wings are compared to conventional aircraft It is also for a given configuration with an optimized wing with a rear engine that is moved more rearward and a high aspect ratio and a small sweep.

  Suitably, a configuration with a large wing range wing can be associated with a configuration having an optimized wing with a high aspect ratio and a small sweep.

  According to a feature, the aircraft has two fairings connected to the wings, a main central landing gear, and two auxiliary landing gears in the form of shock-compensating rocker beams housed in the two fairings, respectively. , Can be provided.

  This makes it possible, in particular, to optimize the possible volume for accommodating the fuel tank and to reduce excessive loads on the wings. Furthermore, the use of an auxiliary landing gear minimizes the height of the fairing while allowing a large landing gear track to provide sufficient stability on the ground.

  Preferably, the associated fairing or fairings is a fairing known as a “Kuchmann” fairing located approximately in the middle of each wing of the wing.

  The advantages of “Kuchmann Carrot” are known to those skilled in the art to improve aircraft performance by using witcam area rules.

  The choice of this type of fairing falls within the synergistic range described above. In fact, the Küchemann fairing is best suited for storage of auxiliary landing gear from this point of view, and thus can be difficult to implement on very delicate wings and / or wings of small relative thickness. Eliminates the need for known landing gear in the section.

  According to another embodiment, the means for moving the at least one masking element, for example comprised of at least one flap, comprises a deformable parallelogram.

  The main advantage of this moving means is that it provides a significant extension of at least one rigid flap while it is very simple (less complex and light). A very noticeable stretch allows the chords of the wings to be very long when deployed, and very close to the noise source to be masked. In particular, this type of configuration can easily and efficiently respond to environmental limitations without significantly changing the design of an aircraft with an already optimized configuration in terms of fuel consumption, maintenance, and operational difficulties. Make it possible.

  According to a feature, the deformable parallelogram comprises at least one torsion bar that moves its parallelogram guided by rotation of the torsion bar, at least one guide arm, and at least one movable rod. To do.

  Preferably, the aircraft wing has a small sweep and a large aspect ratio to improve aerodynamic performance at low and high speeds, thereby reducing fuel consumption. A concomitant effect is a reduction in the volume of the fuel tank.

  For example, the volume can be reduced by 6%, the sweep can be 22 ° or less, and the aspect ratio can be 10 or more. Preferably, the sweep has an angle between 15 ° and 22 °. Thus, the aircraft has excellent performance in takeoff and landing, in particular, has the ability to rise to the sky more quickly and land more slowly. This also contributes to further reduction of noise generated during takeoff and landing.

  Furthermore, because the present invention also has a wing configuration that moves backwards, the aircraft has a wing surface called a leading wing at the front of the fuselage.

  Other features and advantages will become apparent from the following description, given by way of non-limiting example with reference to the accompanying drawings.

1 is a schematic perspective view of an aircraft according to the present invention, the acoustic masking device being in a retracted position. The aircraft of FIG. 1a, whose acoustic masking device is in the deployed position. Fig. 2 shows a schematic model (deficient in the number of propellers) of the noise region generated by the engine mounted on the aircraft of Figs. 1a and 1b. FIG. 2 is a partial top view of the aircraft of FIG. FIG. 4 is a schematic view in cross section along the line AA of the aircraft of FIG. 3. Fig. 4b is a schematic diagram similar to the schematic diagram of Fig. 4a but with a masking device in the retracted position. 1 is a cross-sectional view of a first embodiment of an acoustic masking device in a retracted position. 5b is a cross-sectional view of the masking device of FIG. 5a in a deployed position. FIG. It is sectional drawing of 2nd Embodiment of the acoustic masking apparatus in a retracted position. 6b is a cross-sectional view of the masking device of FIG. 6a in a deployed position. FIG. It is sectional drawing of 3rd Embodiment of the acoustic masking apparatus in a retracted position. 7b is a cross-sectional view of the masking device of FIG. 7a in a deployed position. FIG. FIG. 4 is a schematic perspective view taken along section BB in FIG. 3. It is a schematic sectional drawing of the section CC of FIG. FIG. 6 is a schematic perspective view of a fourth embodiment of an acoustic masking device in a retracted position. FIG. 10b is a schematic perspective view of the masking device of FIG. 10a in a deployed position. 1b is a schematic front view of the aircraft of FIG.

  Figures 1a and 1b show examples of aircraft with reduced environmental impact according to the present invention.

  The aircraft 1 has a longitudinal axis XX ′, and includes a long and thin airframe 2 along the axis, a wing part 4 composed of two symmetric wings 6 and 7, and a horizontal tail unit 8. . The wings 6 and 7 are not equipped with an engine in this embodiment.

  Two piston engines or jet engines are mounted at the rear of the fuselage 2, and more particularly, the turboprop propeller engine 10 has their axis YY ′ (FIG. 2) at the rear of the aircraft 1 with a longitudinal axis. It is configured parallel to XX ′. The turboprop engine 10 is supported by a pylon 12 and is configured to be symmetrically adjacent between the wing portion and the tail unit 8. Each turboprop engine 10 includes a counter-rotating propeller, such as two ductless thrust generating propellers 14 and 16, at the rear. Note that the device is equally applicable to more efficient towed propellers located behind the fuselage. The two propellers 14 and 16 are configured to face each other and be lower than the position of the horizontal tail unit 8.

  During operation, the propellers 14 and 16 of the turboprop engine are interaction noises that extend over the various noise regions shown in FIG. 2 and are directed forward from the turboprop engine as follows, and its axis YY A first region formed by a conical lobe 18 concentrating at, wherein the lobe apex 20 is arranged on an axis YY ′ in the middle of the middle planes aa and bb of the propellers 14 and 16 and An outer conical surface 24 having an apex angle A21 (depending on the particular type of turboprop engine) between the axis YY ′ and around the apex 20 around the apex 20; An apex angle A22 between the inner conical surface 22 and about 20 from the axis YY 'around the apex 20 (in accordance with the specific type of turboprop engine) An inner conical surface 22 having a first region defined between and a second region formed by a conical lobe 26 directed rearward from the turboprop engine and concentrating at its axis YY ′. Where the apex of the lobe 26 is combined with the apex 20 and the rear conical lobe 26 is the outer conical surface 28 and apex angle A28 (turbo) between 40 ° and 60 ° around the apex 20 from the axis YY ′. An outer conical surface 28 having an internal cone surface 30 with an apex angle A30 between 20 ° and 40 ° about axis 20 from axis YY ′ (depending on the particular type of prop engine) Produces an interaction noise defined as a second region defined between the inner conical surface 30 having a shape).

  As shown in FIGS. 1a and 1b, and more particularly in FIG. 3, an acoustic masking device 31 is associated with each of the wings 6, 7 and is at least one movable between a retracted position and a deployed position. A masking element 32 is provided. To achieve this objective, means for moving the masking element are provided as described below.

  The masking element is intended to block the noise region that is directed forward as described above at the developed position. Thus, the perception of noise propagation by the turboprop engine on the ground is reduced.

  Here, the masking element is, for example, a rigid main flap 33 and, for example, a flexible second flap, which is stretched between the front end and the rear portion of the movable flap 33 and fixed to, for example, a longitudinal member of the wing portion. And at least one flap such as a flexible second flap made of fibers 34.

  As shown in FIGS. 4 a and 4 b, the main flap 33 of the masking element 32 blocks the noisy, forward conical lobe 18 when deployed.

  Further, as described above with reference to FIGS. 1a and 1b, the turboprop engine 10 is mounted between the wings 6, 7 and the horizontal tail unit 8 at the rear of the aircraft, so that noisy, rear cones. The lobe 20 is interrupted by the horizontal tail unit 8 itself.

  Therefore, the position of the horizontal tail unit 8 that additionally cooperates with the acoustic masking device 31 allows further reduction of the perception of noise on the ground due to the interaction of the propellers. However, it should be noted that in other configurations, the tail unit may be configured differently, and therefore the noise, rear cone lobe 20 of the turboprop engine is not blocked.

  The second flap 34 constitutes a means for blocking any free space between the movable main flap (blocking flap) and the fixed wing for acoustic reasons. On the other hand, in the case of low-speed flight, the (partially blocked) slot system makes it possible to obtain improved aerodynamic performance. This free space is the fact that the dimensions of the main flap are not sufficient to occupy the entire space between its tip and wings when it is fully moved backwards (deployed position) Is due to. Providing a second flap makes it possible to move the main flap further rearward, especially when the size of the main flap is fixed, and in relation to the chord can be extended in the wing root It becomes. Note that free space can be blocked by one or more rigid flaps.

  As will be explained below, when the masking element is in the retracted position, the masking device may contact the space inside the aircraft wing, or simply the lower surface of the wing, configured for containment purposes. In the space under the wing. In the latter case, in order to accommodate the lower wing shape as smoothly as possible, it is necessary to provide protrusions covering certain elements of the fairing or masking device, so that those in the wing aerodynamics, especially at high speeds. Reduce the influence of existence.

  In the first embodiment of the masking device shown in FIGS. 5a and 5b, the masking element 32 comprises a main flap 33 and a second flap 34 secured to the main flap. The flap 34 is constituted by a flexible fiber that is housed in a wound position as shown in FIGS. 4b and 5a.

  This storage is outside the wing (here the lower wing) when the main flap 33 is in its retracted position (in the rear part including the trailing edge) in a space 35 configured for this purpose within the wing of the aircraft. This is done so that it is flush with the surface. More specifically, the lower part 33a of the flap itself constitutes a part of the lower wing extending from the upstream fixed part 6a of the lower wing. The rear space 35 is designed to leave sufficient space inside the wing to allow the fuel tank to be installed. Thus, the inner region 6b of the wing located upstream of the space 35 can be used to accommodate the fuel tank.

  In addition, the aircraft has a hoist / deployment system 36 that allows the fibers 34 to be rotated or not rotated as required for masking. This system is shown in more detail in FIGS. 5a, 5b, 6a and 6b.

  The winding / deployment system 36 includes a spindle 36a that is housed in the space 35 and around which the fibers 34 are wound. The spindle 36a can be rotated and driven by a spring mechanism (not shown). It should be noted that the spindle is mechanically assisted to move one or more running parts of the system of one or more running parts and one or more running paths that can constitute the means of movement of the masking element 32. . Such a system is described below and illustrated in FIGS.

  The advantage of such an embodiment lies in its very light weight when compared to a second flap that constitutes a rigid flap that is not made of one or more fibers.

  In the second embodiment shown in FIGS. 6 a and 6 b, the masking element 32 comprises a main flap 33 and a second flap constituted by semi-rigid fibers 51. The fibers 51 are constituted by hollow slats that are hinged together so that they can be rotated around the spindle in the manner of a domestic roller shutter.

  In the above-described embodiment, the fibers 51 are further rotated and stored in the space 35 provided in the wing 6 for storage purposes in a manner equivalent to the winding / deployment system 36.

  This second embodiment provides greater robustness to the masking device due to the higher strength of the slatted fabric compared to the fabric fabric.

  In the third embodiment, the masking element 32 comprises a plurality of, for example, three rigid flaps (33, 33 ', 33' ') in FIGS. 7a and 7b. These three flaps (33, 33 ', 33 ") are, for example, in a similar relationship and can slide over each other.

  In this case, each flap is deployed and retracted using, for example, a system of one or more running sections and one or more running paths (not shown in this figure) described below and shown in FIG. Is done.

  In the retracted position, the flaps (33, 33 ', 33 ") are superimposed in the rear interior space 35 inside the wing (Fig. 7a). In the deployed position, the downstream edge of the smallest flap 33 ″ closest to the wing 6 overlaps the upstream edge of the intermediate flap 33 ′. The downstream edge of the intermediate flap 33 'overlaps the upstream edge of the largest flap 33 furthest away from the wing.

  The overlap of the flaps allows the curved surfaces of the joined upper surfaces of the flaps to be smoother, thus making the masking elements they have more overall aerodynamic. Preferably, in the deployed position, the slots between the flaps are reduced to maximize the effect of acoustic masking. However, the aerodynamics of the slot has found a compromise between acoustic efficiency and revenue.

  The third embodiment eliminates the need for a hoisting / deploying system, and can occupy an internal volume substantially equal to the volume of the space 35 as in the two embodiments described above with the hoisting / deploying system.

  Thus, in the deployed position, the extension of the masking elements 32 of the three previously described embodiments significantly extends the chords in the respective wing roots.

  The embodiment shown in FIGS. 7a and 7b is preferred because it is more robust. Various means of the masking element are shown in more detail in FIGS. 8, 9, 10a and 10b.

  8 and 9 show the first possibility for generating these moving means.

  Accordingly, the acoustic masking device 31 comprises a running part and running path system 39 which functions to guide the movement of the running part during the movement of one or more masking elements, for example here the flaps 33. In the embodiment of FIGS. 5a, 5b, 6a, 6b, 7a and 7b, the running section and the runway system guide the main flap 33, and the second element secured thereto follows its movement. Supported.

  As shown in FIG. 8 and also in FIGS. 1 a, 1 b, 3, 4 a and 4 b, the aircraft 1 can include a fairing 37 connected to the wing 4. In this case, these are fairings known as “Kuchmann” fairings and are located approximately in the middle of the respective wings 6, 7 of the wing 4.

  The running section and runway system 39 comprises on the one hand two runways 42 and 43 located in the airframe 2 and fairing 37 respectively, and on the other hand for one of the runways (the running section of the fuselage 2 in FIG. 8). (Only 41 and the running path 42 are shown).

  More specifically, the fuselage runway 42 is located within a cavity formed in the frame 44 of the fuselage 2 so as not to protrude against the outer surface of the fuselage panel 46 for aerodynamic reasons.

  The traveling unit aims to guide the backward translation movement (deployment) and the forward translation movement (retraction) of the main flap 33, while mainly due to the stress caused by the dynamic pressure and the aerodynamic lift. Ensure that the stress is absorbed.

  The traveling part is supported along the movement, for example, using a nut and bolt assembly or by a worm gear mechanism controlled by a push rod. These two solutions are known per se, especially in the field of high lift systems shown in A300B and A320 type commercial aircraft.

  As shown in the schematic cross-sectional view of FIG. 9, the system provides a mechanical connection between the main flap 33 and the travel part 41 (partially shown) in order to provide a hyperstatic mechanical connection as much as possible. A ball joint connection portion is provided therebetween. An equivalent connection is used between the flap and the travel section associated with the travel path 43 (FIG. 8).

  In order to provide play and friction-free movement, a travel section, such as travel section 41 of FIG.

  The lip seal 52 contacts the upper and lower surfaces of the main flap 33, respectively, to prevent water and air from penetrating into the respective cavities that receive one of the running sections and one of the running paths 42, 43. To do.

  According to a second possible embodiment shown in FIGS. 10 a, 10 b, the means for moving the masking element 32 of the acoustic masking device 31 comprise a deformable parallelogram 54. In these drawings, the masking element 32 is constituted by a single flap 55.

  The deformable parallelogram 54 is constituted by two guide arms 56 and two movable rods 58.

  A guide arm 56 having an equal, elongated shape, with a small thickness and width, gradually increases from one end of the rod to the other.

  One end A of the guide arm 56 is fixed to the masking element 32 by the inner surface of the guide arm 56 while being near the upstream end but spaced from the upstream end. The opposite end D of the guide arm 56 remains free.

  Each guide arm remains in permanent contact with the slidable movable rod 58 at one point.

  The movable rod 58 has a general shape similar to the shape of the guide arm 56.

  One of their ends B is fixed to the upstream end of the masking element 32 by its inner surface, and their opposite ends C are on a torsion bar 60 oriented perpendicular to their longitudinal axis, e.g. Fixed by built-in.

  The torsion bar 60 is shown in the form of a tube. The movement about the axis Y shown in FIGS. 10a and 10b was accommodated by a telescopic cylinder (not shown) housed between the wing flap and the stringer or by the fuselage. Guided by a rotating cylinder (not shown).

  The load bearing rod 62 absorbs the load perpendicular to the plane of the guide arm 56 and thus makes it possible to limit the inertia of the rod.

  The acoustic masking device is located below the wing and the torsion bar 60 is connected to the stringer by a strong rib and using a support (not shown).

  In the modified example (not shown) of the first embodiment, the weight of the guide arm 56 is increased to eliminate the load bearing rod 62.

  In an embodiment according to the second variant (not shown), the masking element 32 comprises two flaps, with an additional support half-way between the supports connecting the first flap to the wing. Added.

  In an embodiment (not shown) according to a third variant, the torsion bar 60 is no longer used for performing the movement, but is used for synchronizing the movement of the movable rod and the guide arm. The cylinder is then added at each support location.

  The mechanism composed of a deformable parallelogram has the advantage of being widely accommodated within the thickness of the wing 4. Only two small protrusions in the lower wing skin are required to surround the ends A and B, which extend slightly beyond the shape. This makes it possible to avoid the addition of flap runways and associated fairings at the position of the lower surface of the wing.

  This second possible embodiment is for a wing with a large internal volume known as the “Yehudi” between the trailing edge knee and the fuselage (the internal volume located inside the trailing edge knee). Particularly preferred. Furthermore, this second possible component has the advantage of simplicity and its weight is as small as the resulting aerodynamic penalties.

  In a typical configuration, the wings of the aircraft as in FIGS. 1a and 1b are not equipped with an engine and are not moved behind the aircraft as compared to their position in the aircraft, especially commercial aircraft, (The backward movement position of the wing means the position of the wing further away from the nose.) The wing is located away from the nose of the aircraft and is between 50% and 55% of the length of the fuselage. Therefore, backward movement means in this case a wing located more than 55% of the length of the fuselage, and in any case, slightly backwards with the addition of an acoustic masking system according to the invention. It means a wing that is just moved. This general configuration is the wing aspect that increases the maximum aerodynamic lift of the aircraft and thereby improves low speed performance, reduces sweeps, and gives them a high lift ratio. Allows aerodynamic features such as increased ratio (ratio of wing width to wing surface square).

  Thus, aircraft have superior performance in take-off and landing, particularly the ability to rise faster to the sky and land more slowly. This also contributes to further reduction of noise generated during takeoff and landing.

  In addition, this optimized configuration can significantly improve aircraft performance with respect to fuel consumption and drag reduction. In fact, the aspect ratio reduces the drag that occurs, and the reduction in sweep allows a partially streamlined wing to be envisaged. In the case of such a configuration, a flap system using one or more traveling parts and one or more traveling road movements is suitable as well as the use of so-called Kuchmann fairing.

  Preferably, the sweep is 22 ° or less and the aspect ratio is 10 or more. Preferably, the aspect ratio is comprised between 10 and 14, and the sweep is comprised between 17 ° and 22 ° (a sweep that is too low requires a lower cruise speed).

  As shown in FIG. 11, the aircraft 1 further includes a fairing 37, a landing gear 38, and two auxiliary landing gears 40 in the form of impact compensation rocker beams.

  The landing gear is accommodated in the fairing 37.

  The impact landing rocker beam type auxiliary landing gear 40 is known to those skilled in the art under the names B-47, B-52, U-2, for example, or different names.

  The advantage of the configuration shown in FIG. 11 is that the wings 4 do not require the support of the central landing gear, thus reducing the load and allowing the dimensions of the fairing 37 to be minimized. .

  Thus, to improve performance, the wings do not need to be large enough to accommodate landing gear with sufficient runway to provide ground stability. Further, the wing sweep can be further reduced, and the aspect ratio can be further increased.

  However, it should be noted that the present invention does not exclude the case where the wings need to be moved backwards to the extent that they need to add a wing surface, called the leading wing, to the front of the fuselage.

  The acoustic masking device greatly contributes to the reduction of noise recognized on the ground, and constitutes other elements such as setting the wing part backward or extending the chord. According to a specific configuration, a masking element having a length of 1.5 m (maximum on the order of 2.2 m) has the same effect as a joint extension of the tail unit and 20% wing chord. .

  Although the drawings are merely examples of an aircraft having a turboprop engine with a propeller, the concept can be applied to aircraft with other types of engines such as turbofans located in the wings at the rear of the fuselage. .

  These aircraft are generally aircraft of the SFN (side fuselage engine room) type with two engines located on either side (or RFN) of the rear of the fuselage.

  In the case of the upstream noise region generated by the fan, the predetermined position of the engine relative to the aircraft axis is located at the position of the wing root. Therefore, it can be blocked by the acoustic masking device according to the present invention.

Claims (17)

An aircraft with reduced environmental impact,
At least one engine (10) attached to the rear of the aircraft to generate noise forward;
A wing (4),
In an aircraft in which the noise generated by the at least one engine is diffused into a noise region (18),
The aircraft
At least one acoustic masking device (31), one retracted position;
A deployment position in another deployment position, wherein at least one masking element blocks the noise region (18) to reduce ground perception of the noise spread by the at least one engine (10);
An acoustic masking device (31) having at least one said masking element (32) movable between
Aircraft characterized in that the acoustic masking element (32) is moved backwards to extend the chord in the root of the wing (4) in the deployed position.   The aircraft according to claim 1, characterized in that the masking element (32) is in a retracted position during the cruise phase and in a deployed position during the takeoff phase, landing phase and / or approach phase. Further comprising an airframe (2) having a wing (4) with two symmetrical wings (6, 7);
3. The method according to claim 1, wherein the at least one engine (10) is mounted between the wings (6, 7) and the rear end of the aircraft at the rear of the aircraft. The aircraft according to one. The aircraft further comprises a fuselage (2) having a wing (4) with two symmetrical wings (6, 7), and at least one horizontal tail unit (8);
The at least one engine (10) is mounted between the wings (6, 7) and the horizontal tail unit (8) at the rear of the aircraft;
An acoustic masking device (31) is associated with each of the wings (6, 7);
At least one masking element (32) of each acoustic masking device (31) is between a retracted position and a deployed position to extend the chord in the respective root of the wing (6, 7). The aircraft according to any one of claims 1 to 3, wherein the aircraft is movable.   5. An aircraft according to any one of the preceding claims, wherein at least one of the acoustic masking devices (31) comprises means for moving at least one of the masking elements (32).   The at least one masking element (32) of at least one of the acoustic masking devices comprises at least one flap (33). aircraft.   The aircraft according to claim 6, characterized in that at least one said masking element (32) comprises a main flap (33) and at least one second flap (33 ', 33 ", 34).   The aircraft according to claim 7, characterized in that the main flap (33) is rigid and at least one of the second flaps consists of flexible fibers (34).   9. An aircraft according to claim 8, wherein at least one of the acoustic masking devices (31) comprises a winding / unfolding system (36) that allows the flexible fibers (34) to be rolled up and deployed. .   At least one acoustic masking device (31) functions to guide the movement of the travel part (41) when the at least one masking element (32) is moved; 10. Aircraft according to any one of the preceding claims, characterized in that it comprises a system (39) of a plurality of runways. The aircraft further comprises at least one fairing (37) connected to the wing (4);
The system (39) of the one or more traveling units and the one or more traveling paths includes two traveling paths (42, 43) respectively accommodated in the airframe (2) and at least one fairing (37). The aircraft according to claim 10.   The aircraft is in the form of two fairings (37) connected to the wings (4), a central landing gear (38), and an impact-compensating rocker beam type housed in each of the two fairings (37). The aircraft according to any one of claims 10 or 11, further comprising two auxiliary landing gears (40).   The one or more fairings (37) are known as “Kuchmann” fairings located approximately in the middle of the wings (6, 7) of the wings (2), respectively. An aircraft according to any one of claims 11 or 12.   6. An aircraft according to claim 5, characterized in that the moving means of at least one of the masking elements (32) comprises a deformable parallelogram (54).   The deformable parallelogram (54) comprises at least one torsion bar (60), at least one guide arm (56), and at least one movable rod (58), wherein the parallelogram The aircraft according to claim 14, characterized in that the movement of (54) is guided by the rotation of the torsion bar (60).   5. An aircraft according to claim 3, wherein the wings (6, 7) have a small sweep and a high aspect ratio to reduce fuel consumption.   The aircraft according to any one of the preceding claims, characterized in that the aircraft further comprises a wing surface called a leading wing at the front of the fuselage (2).

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